1. Field of the Invention
The present invention relates to an amplifier circuit and, more particularly, to an amplifier circuit used in an optical transmitter.
2. Related Background Art
In the field of optical communication, optical transmitters are used as devices for converting an input electric signal to an optical signal and sending the optical signal as an output signal to a transmission line (e.g., cf. Japanese Patent Application Laid-Open Publication No. 2012-215662). The optical transmitter described in the Publication No 2012-215662 is provided with a laser diode which outputs continuous wave (CW) light, a modulator which modulates the intensity of the CW light output from the laser diode and outputs the modulated light as an optical signal, and a modulator driving circuit for generating a driving signal to drive the modulator based on an input electric signal.
The optical transmitter described in the Publication No. 2012-215662 is further provided with an amplitude detection circuit for detecting the amplitude of the input signal and with a controller for generating a waveform control signal based on the amplitude of the input signal detected by the amplitude detection circuit. The modulator driving circuit controls the waveform of the driving signal, based on the waveform control signal generated by the controller. As constructed in this configuration, the optical transmitter described in the Publication No. 2012-215662 compensates variation in the amplitude of the input signal with the waveform control signal in order to keep the waveform of the optical output from the optical transmitter.